Shower mixer cannot regulate and is only hot or cold?

My shower is either boiling hot or freezing cold. When turning the termostat control it does not regulate the temperature, it simply turns directly to hot at a certain point and then directly back to cold.
Lee Campbell, May 2005


done
If its a new installation it is possible that the hot and cold pipes are mixed up. If it is possible to remove the facia of the shower after it has been run hot you can feel which is the hot pipe. there should be a red and blue mark on the inlets to the mixer. If tehre are no marker you will hadve to turn off the stop-cocks to the pipes and just swap them to see.

rory, May 2005